Preparation of alktl esters



June 3, 1941.

H. G. VESTERDAI PREPARATION OF ALKYL ESTERS Filed Nov. 24, 1937 HYDROLYZEA .5 TIQIILPP liva TOWE a alcohols.

Patented June 3, 1941 UNITED STATES PATENT OFFICE PREPARATION OF ALKYL ESTER-S Hans G. Vesterdal, Elizabeth, N. J., ass'ignor to Standard Alcohol Company Application November 24, 1937, Serial No. 176,165

6Claims.

of the mineral acid. These esters can be hydrolyzed to form alcohols. ticularly concerned with the process of using a mixture of phosphoric acid and fuming sulphuric acid to esterify the olefines whereby the yield of alcohols is increased and the polymer formation greatly diminished. The invention especially relates to increasing the speed of reaction in the manufacture of higher alcohols whereby higher olefins may be treated in a continuous system for a very limited time of contact with. a minimum of polymer formation.

It is well known to treat unsaturated hydrocarbons such as ethylene, propylene and the like with sulphuric acid to form the corresponding esters and then to hydrolyze said esters by means of water and to distill oi? the alcohols formed. In this process it is desirable to accelerate the reaction thereby increasing the capacity of the treating equipment by treating with relatively strong or fuming sulphuric acid. This,

however; has the disadvantage in that it greatly increases the amount of undesirable polymer formation with the resulting decrease in yield of mixture of fuming sulphuric acid and phosphoric acid greatly accelerates the reaction and diminishes the time of contact while at the same time the process increases yields of alcohol and decreases the undesirable polymer yield to a minimum.

The invention will be more clearly understood by referring to the drawing which shows a typical flow plan showing one particular modification of the invention. This process flow plan given for illustration relates particularly to the manufacture of butyl alcohol from butylenes. In this process a raw liquid fraction known in the petroleum industry as a butane cut containing butylenes, which has been segregated with suitable equipment ior instance from refinery gases evolved from petroleum distilling, cracking and naphtha reforming operations, is fed into agitator l by means of feed line 2. A mixture of fuming sulphuric acid and phosphoric acid of the desired strength is introduced into agitator I by means of feed line 3 and a complete mixing secured by the revolving stirrer 4. The unreacted The invention is par- The present invention by utilizing a perature of about 75 C.

materialsof the butane out are removed from agitator I by means of line 5 and are suitably treated as, for example, with a caustic solution to remove any entrained acid and are then used for other purposes. The acid olefin reaction liquor of agitator l containing isobutyl acid sulfate and diisobutyl acid phosphate is withdrawn from agitator l by means of line 6 and intro,

duced into'hydrolyzer I, wherein it is thoroughly mixed by means of stirrer 9 with water introduced through line Ill. The reaction products comprising butyl alcohol, sulphuric acid, phosphoric acid and water, are introduced into steam stripping tower I I through line 12 wherein the alcohols are separated and taken overhead through line l3 while the other products are removed through line I4.

The process may be varied or altered within wide limits. For example, temperatures, pressures, acid strength, feed rates and any particular method of mixing or treating may be widely varied. e conditions are adapted to the particular olefins or to the particular mixture of olefins or to the olefin containing fraction which is being treated in order to secure various products and optimum yields as, for example, in order to secure a maximum yield of a particular alcohol such as butyl alcohol. For example, in the man ufacture of butyl alcohols from a butane cut fraction containing butylenes, it is desirable to use an acid mixture of approximately 50 volumes of sulphuric acid containing 20% by weight of free sulphur trioxide and 50 volumes of 85% by weight phosphoric acid. In this operation it is desirable to maintain a pressure of approximately 25 pounds gauge and a temperature of about F, in agitator i. In the manufacture of isopropyl alcohol an acid mixture of approximately volumes sulphuric acid containing 20% by weight free sulphur trioxide and 25 volumes of 85% by weight phosphoric acid is desirable. In this process tow-er I is maintained at a pressure of about pounds gauge and at a tem- In the manufacture of amyl and hexyl alcohol from. a so-called pentanehexane cut, segregated by means of suitable fractionating equipment from refinery gases secured by distilling, cracking and naphtha reforming operations, an acid mixture of about 75 volumes of sulphuric acid containing approximately 20% by weight of free sulphur trioxide and 25 volumes of by weight phosphoric acid is preferred. The temperature of agitator l in this operation is preferably maintained between 10 and 50 F., preferably at a temperature of about preferably in the range from 30 to 60 F. e

pressure employed in the manufacture of l hexyl and heptyl alcohol is preferably atmos pheric although higher pressures may be em= ,ployed- The preferred acid mixture in the man= ufacture of heptyl alcohol is 75 volumes'of sul phuric'acid containing 65% by weight of free sulphur trioxide and 25 volumes of 85% by weight of phosphoric acid.

The following examples are given as specific methods of making alcohols and serve to illus- 2,243,991 35"- F. In the manufacture oi heptyl alcohol,

sulphuric acid.

EXAMPLE 2 A hydrocarbon fraction, known in the petroieum industry as cracked wax, was distilled and the fraction boiling in the heptane range was segregated. This heptane fraction was then Suliatz'on of a heptane fraction from cracked wax trate the invention: followed by hydrolysis to produce heptyl alcohol Yields vol. based Volumes upon heptane fraction present Sulfating agent Temper- Time of V store contact- Hepinne Sulfsting fraction reagent Alcohol Polymer a F. Sewn A 100 41 95% also. 110-120 ,510 16.6 B '100 24 Fumm nssm, 20% so, so 110 34.. 5 10. 8 c .100 Fuming H1300, 65% so 85% phosphoric can. 50 115 22. 2 5 D 100 Fumm 'msoa, 05% so. 85% phosphoric mm--- 35-40 114 26 4. 8

EXAMPLE 1 30 These results demonstrate that for the same A hydrocarbon fraction boiling in the pentanehexane range and known in refinery practice as a pentane-hexane cut, was segregated by means of suitable distilling equipment. This material, having an analysis of apprommately 66% pentanes and hexanes and 34% pentenes and hexenes, was then sulfated with various sulfating agents under difierent conditions to form derivatives and was then hydrolyzed to produce amyl and hexyl alcohols. The following table summ'arizes the respective results secured:

Suljaticm of a pentane-hea'ane fraction, followed yield of alcohol, the time of contact may be reduced to one-fifth by the process of the present invention, resulting in the formation of only 25% of the undesirable polymers secured when usin -desirable to secure a particular product. Feed rates may be adjusted to secure optimum yields of the particular product desired.

For example, a petroleum fraction known in V by hydrolysis to produce amyl and hem; the petroleum industry as a butane cut, maybe I alcohols 5 segregated from the refinery. gases by means of Yields vol. based Volumes upon politeneshexsnes present Temper- Time oi Bulfsting agent More contact lgentane sumflng A h 1 P y 928116 00 0 0 81' traction reagent F. A 100 10 95% mso. so than... 24.1 9.7 B 100 1s -Fuming msod, 20% s08 35-40 aooseon 25.0 47.0 '0 100 1g Fuming H1804, 20% 80a 85%phosphorio scld... 35-40 305 sec 25.0 4.7 n 100 & Fuming msol, zc%soiss%. hosphonc acid---. 35-40 76 sec--. 31.9 17.7

results of B and D demonstrates that the process of the present inventionmay increase the yield approximately with a time of contact of 76 suitable distilling equipment. This butane cut has approximately the following analysis:

- Percent' Isobutane 15 Beta butylen 18 Isobutylene 14. Alpha buty 7 Normal butane 46 This feed material is led into agitator i and treated with an acid mixture of 50 volumes of sulphuric acid containing 20% by weight of sul- .phur tridxide and 50 volumes of 85% by weight of phosphoric acid. The temperature of agitator seconds as compared to 300 seconds when using l is -maintained at about from 60 F. to F.

fuming sulphuric acid. The yield of polymer is 17.7 as compared to 47 when using the fuming.

v at a piiessure or about 25 pounds gauge. The I claim-a spent naphtha and the acid derivatives are being 1. Process for the production or eaters ircm treated in the manner described. Conditions cieflm comprising contacting said oleilns oi msythusbesuitably adiustedinthe manuiachigher molecular weightthanethylene wit-ha tureoipropylorotheralcohols. 5 mixtureoiphosphcricacidandiumingsulturic Thepresentinventionisdesirableinthatit acidtoiormacidoleilnesteraunderconditions secures a high speed oi reaction which permits under which no substantial sultonation oi the large throughputs and yields tor a fixed capacoleilns takes place. I

ity. The invention also secureshigh yields in 2. Processin accordance with claim 1 iuwhich tbat it greatly decreases the amount oi'undesaid acid mixture ccmprisa 50 to 75% .by volsirable polymer iormation since, there is contime of oleum and to 50% by volume of siderablyless tendency to polymerize the oleilns 85% phosphoric acid. 1 than -when'using vturning sulphuric acid. It is 3. Process for the,production oi esters i'rcm particularly desirable in that it permits the prooleflns oi higher molecular weight than ethylene duction of higher alcohols having more than 6 L15 comprising contacting said oieflns with a mixcarbbnatoms in the molecule from the'higher tureoi phosphoric and fuming sulturicacidsat oleiln whichrheretoiore has not been practical a uniavcrable to suli'onadue to excessive polymerization. The process of tion ior af'time oiijcontactoiless than-two minthe present invention by nea ly increasing the utes to tom-acid olefin esters. speed oi reaction permits these alcohols to he go 4. Proceasinaccordancewithclaimflnwhicli manufactured in a continuous process without the olefin is in a hydrocarbon liquid containing a undue polymer formation.

'l'heieedmaterialmaybepureoleiinesormix 5.ln accordancewithclaim8inwhich oi pure oleflnes. .lhe olennes may also a hydrocarbon liquid containing a substantial be ccntainedinhydrocarbons which do-nct react. g5 proportion of pentenes andhexenes is treated withtheacidmixtur e. Preierredieedmaterials' withamixtureci phosphoric acidandtuming are hydrocarbon fractions containin? lmsatusulturicacid containing 2556 toio'b by volume ratedmaterialssecuredinreflningmrackingand c1855. phos'phoricacidandbil'k-to'lifl. by voldistilling operations.- 7

By this process, oleflnes containing 10 to 183 suliurtrioaideioratimeoicontactctlessthan carbon atoms in the molecule may be treated at two minutes andat a temperature of abcut 35 a short time or contact to produce. the corre I to tormacidoleiln esters.

spending alkylcompoundsoithemineraiacids. bsrrocessinaccordancewithcla'im ainwhich These acid alkyl sulfates and phosphates may a hydrocarbonliquid containing a substantial ,-be hydrolysed-to the corresponding alcohols'or s5 proportion of hexenes and heptenes is treated they maybe neutralized with a suitable base to with a mixture oi phosphoric acid and fuming iorm detergents. 1 sulfuric acid at about 40' to about Y 'Ihe present invention is not to be limited by time of contact ot less thantwo minutestodorm any particular example "given .or by any theory 1 acid bexyl and heptyl esters. a

oi operation but only by the iollowingclalms in 40 which it isvdesired to claim all novelty inso tar v BARF G.

. as the prior art permits. 

